In conventional face-cooled, face-pumped slab lasers shown in FIG. 1(a) and FIG. 1(b), active medium 10 is pumped through faces 11 and 12 by flashlamps 23 and 24, respectively, to excite atoms of the active medium 10 to a metastable state and thereby produce a population inversion therein. Heretofore, the flashlamp pumping radiation excites atoms around the optical path of the flashlamp pumping radiation through the slab.
However, in the conventional laser device described above, the length of said optical path is only about a thickness d of the slab-geometry laser medium 10; i.e., the effective optical path through the slab for the flashlamp pumping radiation is relatively short. As a result, the energy transfer efficiency from the flashlamp radiation energy to the laser slab storage energy is small.
Moreover, the use of flashlamp in pumping solid-state ion lasers has several drawbacks. Firstly, the ratio of flashlamp radiation within the absorption bands of the laser material to the total lamp radiation is small. This is because the lamp radiation covers a broad spectrum, whereas the absorption bands for most of the solid-state ion laser materials (e.g., Ruby, Nd:YAG, Nd:GGG, etc.) are narrow. As a result, a substantial part of the pump radiation energy is not transferred to the storage energy in the laser slab. Secondly, the short wavelength (i.e. UV) radiation from the flashlamp output is parasitic to the laser material by creation of color center in the laser medium, which can degrade laser performance, as well as increase the thermal load in the laser medium. Thirdly, the lifetime of the flashlamps is relatively short, since the large discharge current is supplied to the flashlamp.